(a) Field of the Invention
The present invention relates to an overcoated sheet used as a transfer sheet for use in a plain-paper copier, a drafting film, a diazo second original film or the like.
(b) Description of the Prior Art
The overcoated film, which is used as a transfer sheet for use in a plain-paper copier, a drafting film, a diazo second original film or the like, is required to possess a writing ability with a pencil, a water-color ink or an oil-color ink or the like, an erasability (or amendability) of an ink or a toner with eraser or an amending liquid (solvent), an adhering property to a toner or the like. In relation to these properties, additionally, the overcoated film is required to have a sufficient hardness, solvent-resistance and the like so that the overcoat layer may not be damaged or dissolved during writing (especially with a hard pencil) or during amending, a thermal stability to such an extent that materials may not be modified or decompose at the time of thermofitting a toner, and the like.
As the overcoated sheet like this there has hitherto been known the one which comprises forming, on at least one side of a substrate such as paper, plastic film or the like, if needed, a matted layer consisting essentially of a binder such as a thermoplastic resin like an acrylic acid resin, a thermo-setting resin like an amino resin and so forth and a matting agent, and thereafter forming thereon an overcoat layer consisting essentially of a water soluble resin such as a high polymer electrolyte and/or PVA.
However, any one of the conventional overcoated sheets could not satisfy the aforesaid requisite performance wholly and simultaneously.